Genesee Fire Rescue
CommunityWildfireMeeting
Denver Fire at Black Forest Fire
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EP
Convection
Radiation
Conduction
Heat Transfer
Three environmental factors of wildfire behavior that affect the
spread of wildland fire.
TemperatureWind
Increases supply of oxygen.Drives convective heat into adjacent fuels.Influences direction of spread and spotting.Carries away moist air replacing it with drier air.Dries fuels.Raises fuel moisture if the air contains moisture.
Relative HumidityAs RH increases, fuel moisture increases.
PrecipitationIncreases fuel moisture
Weather
Strong Wind.Sudden changes in wind direction and velocity due to
weather fronts.High, fast-moving clouds may indicate unusual surface
winds.Unexpected calm may indicate wind shift.Thunderstorms above or close to the fire.Unusually high temperatures and low relative humidity.Dust devils and whirlwinds developing.Bent smoke column.
Indicators of Problem and Extreme Fire Behavior
Weather Indicators
Aspect
SOUTH
NORTH
Heavy fuelsShadeMoist
Topography
Light fuelsSunnyDry
Steep Slopes Cause Rapid Fire Spread
Flame is closer to
and preheating
fuel
Convection and Radiant Heat
Box Canyon & Chimney Effect
Radiant HeatAcross Narrow Canyon
Spotting Across Narrow Canyon
Mountains CauseChanneling of Wind
Indicators of Problem and Extreme Fire Behavior
Steep slopes.Chutes, saddles, and box canyons which
provide conditions for “chimney effect.”Narrow canyons may increase fire spread
by radiant heat and spotting.
Topography Indicators
Fuel Characteristics
Fuel Moisture Size and Shape Fuel Loading Horizontal Continuity Vertical Arrangement
Fuels
Fuel MoistureThe amount of water in a fuel
expressed as a percentage of the oven-dry weight of that fuel.
CATEGORIES
• 1-hour fuels: 0 – ¼ inch in diameter• 10-hour fuels: ¼ – 1 inch in diameter• 100-hour fuels: 1 – 3 inches in
diameter• 1000-hour fuels: 3 – 8 inches in
diameter
Categories of FuelLight Fuels: Leaves Grass Shrubs
Heavy Fuels: Limbs Logs Stumps
Fuel Loading
The quantity of fuels in an area
Horizontal Continuity &Vertical Arrangement
Horizontal Continuity: Uniform Patchy
Vertical Arrangement: Ground Surface Aerial
Uniform Fuels
Patchy Fuels
Vertical Arrangement of Fuels
Aerial Fuels
Ladder Fuels
Surface Fuels
Ground Fuels
Unusually dry fuels.Large amount of light fuel (shrubs, grass,
needles).Fuels exposed to direct sunlight.Fuels dried by prolonged drought.Ladder fuels that allow a surface fire to move
into the crowns of shrubs or trees.Crown foliage dried by surface fire.Concentration of snags.
Indicators of Problem and Extreme Fire Behavior
Fuel Indicators
Fire Behavior Terms
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CreepingFire burning with a low flame and
spreading slowly.
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RunningFire spread rapidly with a well defined head.
*Click on image to play video
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SpottingFire producing sparks or embers that are carried by
the wind or convection that start new fires
*Click on image to play video
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Torching
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Flare upSudden acceleration of fire spread or intensity, but of
relatively short duration.
Fire WhirlA spinning, moving column of ascending air rising within
a vortex and carrying aloft smoke, debris, and flames.
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CrowningFire advances from top-to-top of trees or shrubs more or less independently of the surface fire.
*Click on image to play video
Keep an eye on the smoke column. Indicates direction of fire spread, location of spot fires, and changes in fire intensity.
Many simultaneous fires starting or smoldering fires beginning to pick up in intensity.
Fire begins to torch small groups of trees or shrubs.Frequent spot fires occurring.Fire-whirls beginning to develop inside the main fire.Crown fires.
Indicators of Problem and Extreme Fire Behavior
Fire Behavior Indicators
Tactical Modes
Offensive
Defensive
Combination
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Attack and contain the fire
Offensive Mode
Defensive Mode
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Set up at the houseClear flammable materialProtect house from flame and sparks
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If too much fire or no defensible space, LEAVE!Return after fire front passes
Defensive Mode
Structure engines at home for protection
Attack fire and and drive flames away from house
CombinationOffensive and Defensive Mode
# 1
# 2 # 3
# 4
Structure Triage “Size-Up”
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1. Well-irrigated area encircling structure for at least 30 feet on all sides. Plantings limited to carefully spaced low flammability species.
2. Provide added protection with “Fuel Breaks” like driveways, gravel walkways and lawns.
5 Top Effective Mitigation MeasuresCase Study of Witch and Guejito Fires
3. Keep vegetation pruned and limb trees 6–10 feet from ground. Remove leaf /needle clutter and dead and overhanging branches.
4. Periodically inspect your property, clearing dead wood and dense vegetation at a distance of at least 30 feet from your house.
5. Is the structure free of an attached wood fence?
Footnote: Of the 241 homes impacted, 13 had wood shake roofs and all 13 were destroyed. A total of 89 were destroyed or damaged.
Waldo Canyon Fire - 2012
Fire Brand Experiment
Shut off natural gas and propane. Place metal (not wooden) ladders against the lee side
of your house. Connect and turn off outside water hoses and nozzles. If time permits, remove combustibles (patio furniture,
firewood, etc.) within 30 feet of your home. Close windows and doors to the house to prevent
sparks and embers from blowing inside. Cover gable vents if time permits.
Close all doors inside the house to prevent draft. Turn OFF fans, air conditioner, furnace.
Things YOU can do to help us
Move furniture from windows. Take down your drapes and curtains and close all
blinds to deflect heat. Fill all bathtubs, sinks and other containers with
water to deflect heat. Leave exterior lights on so responders can find your
home at night. Put on natural fiber clothing and take your 72-Hour
kit with you. Leave front door unlocked. Put a white flag (towel, pillow case, etc.) outside
where it can be seen from the roadway.
Only Do The Above IF YOU HAVE TIMEEvacuate Now Means NOW
Black Forest Fire 2013 – Video courtesy of Colorado Springs Fire Department
Questions?
Genesee Fire Rescue